The present invention relates generally to a release ski binding of the type having a sole plate that can be fastened under the sole of a boot for skiing; the extremities of said plate being constantly urged toward the ski by one or more flexible connections such as cables, subjected at all times to the action of one or more elastic tension devices. More particularly, the distal end of at least one of the flexible connections is fastened to the ski by means of a hooking head which is slidably and pivotally mounted on the ski around a spindle that is anchored roughly perpendicular to the upper surface of the latter. The end of the plate is kept locked during skiing against this head.
In a known ski binding of this type, the cable is anchored directly to a spindle or axis. When a minimum pre-set force is exerted upward by the boot on the plate, it is necessary that the end of the plate which is locked under an inclined edge of the hooking head of the anchor free itself from said edge and be able to move upward in relation to the ski. For this purpose, the plate has to move away from the hooking head. However, this movement tends to be prevented not only by the tension of the cable that connects the plate to the pivoting head, but also by a component of the tension of the second cable that connects the opposite end of the plate to the ski. Therefore, the positioning of anchor of the second cable on the ski is very important because a poor positioning is liable to disturb the release of the first end of the plate by increasing or decreasing the amount of force necessary for such release. The fact is that such a positioning is difficult to achieve, because it is done without the possibility of adjustment at the time that the binding is installed on the ski.
Also, when a minimum pre-set force is exerted laterally by the boot on the plate, it is necessary that the end of the plate be able to release and move laterally with respect to the ski. In the past, the end of the plate had a recess in the center, shaped in such a way that it fit on either side of the pivoting head. Since the lateral releasing force must be three or four times less than the upward releasing force, the width of this recess was relatively small because a greater width would produce an arching of the lateral parts of the pivoting head on the lateral parts of the recess of the plate so that the latter would move back considerably, which would require an increase in the minimum release force. As a result of this relatively small width of the recess in the plate, the plate is maintained in position against the pivoting head by relatively close points of support. In view of the lnormal amount of play inherent in manufacturing operations, it has heretofore been difficult to obtain a very good lateral stability of the plate on the ski during skiing.
Furthermore, after upward and/or lateral release, the plate should be able to resume its place automatically on the ski, with its front extremity coming back to lock against the pivoting head under the action of the cable connecting it to the head. However, this return to a skiing position is sometimes disrupted because of the tension of the rear connection, and also of the front connection, that tend to return the plate too rapidly. In such cases the end of the plate strikes against the upper part of the pivoting head; and in order for locking to be able to take place, the plate has to move back against the tension of the two cables which occasionally does not occur due to the inertia of the plate and of the skier that it supports, said inertia often tending to pull the plate in the direction of the pivoting head.
The ski binding according to the present invention makes it possible to avoid these prior problems. It permits a release in all directions and an automatic return of the plate onto the ski once the force that produced the release ceases to be applied, with the end of the plate always locking against the head automatically, without the plate having to move away from the pivoting head for this purpose. Furthermore, the recess in the plate's extremity can be given greater dimensions and in particular a greater width, so that the points of support of the plate and pivoting head can be placed further apart. This permits greater lateral stability of the plate during skiing, without this greater distance in the supporting points interfering with the release of the plate or with its return to a locked position. Finally, the ski can bend longitudinally during skiing, and this flexing likewise does not interfere with the release or locking of the plate.